Orthodontic brackets represent a principal component of all corrective orthodontic treatments devoted to improving a patient's occlusion. In conventional orthodontic treatments, a clinician or an assistant affixes brackets to the patient's teeth and then engages an archwire into a slot of each bracket. The archwire applies corrective forces that coerce the teeth to move into correct orthodontic positions. Traditional ligatures, such as small elastomeric O-rings or elastic power chains may be employed to retain the archwire within each bracket slot by way of tie wings.
Self-ligating orthodontic brackets have been developed that eliminate the need for ligatures by relying on a movable member, such as a latch or slide, for retaining the archwire within the bracket slot. However, many self-ligating orthodontic brackets include tie wings and employ ligatures or power chains that secure the archwire within the archwire slot during selected stages of orthodontic treatment. Ligatures or power chains may facilitate coupling of the bracket to other adjacent orthodontic devices.
Traditionally, a ligature or a power chain is manually engaged by the clinician by stretching it over the bracket and the archwire and securing it under the tie wings. The ligature remains in a stretched condition during treatment. During installation, once the ligature or power chain has cleared a corner of the bracket, the elasticity of the ligature or power chain, as a result of it being stretched, pulls it into the area under the tie wing (the “under-tie wing area”), effectively seating the ligature to the orthodontic bracket and securing the archwire to the orthodontic bracket. During this installation process, the ligature or power chain must be elastic enough to clear the corner of the bracket and then retract enough to sufficiently secure the archwire to the orthodontic bracket. In some instances, the large degree of stretching causes ligatures to break during use.
By way of example, ligatures may break when they are stretched during installation onto a bracket. When this occurs, the orthodontist must remove the broken ligature and secure another ligature in its place. In addition, it is not uncommon for ligatures to break after initial installation and during treatment. As such, this type of breakage typically occurs when the patient is not at the clinician's office. As a consequence, the patient may make an unplanned visit to the clinician to replace the broken ligature. During the time between ligature breakage and the office visit, orthodontic treatment may not be as efficient or according to the orthodontist's treatment plan. This may, in turn, increase treatment time and the time the patient must wear the braces.
Therefore, a need exists for orthodontic brackets that reduce the risk of ligature failure and facilitate ligature installation.